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help / color / mirror / Atom feedprint_path is missing GatherMerge and CustomScan support
14+ messages / 5 participants
[nested] [flat]
Commits from this thread:
2018-07-19 b33ef397a1 bc62aef53d 49d506dd21 164ed1532f 3ecd6c4ab9 Fix print of Path nodes when using OPTIMIZER_DEBUG
2018-07-19 c6598b8b05 6365ebacdd Fix re-parameterize of MergeAppendPath
* print_path is missing GatherMerge and CustomScan support
@ 2018-07-18 05:35 Masahiko Sawada <sawada.mshk@gmail.com>
0 siblings, 1 reply; 14+ messages in thread
From: Masahiko Sawada @ 2018-07-18 05:35 UTC (permalink / raw)
To: pgsql-hackers
Hi,
While debugging planner I realized that print_path() function is not
aware of both GatherMerge path and CustomScan path. Attached small
patch fixes it.
Regards,
--
Masahiko Sawada
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center
Attachments:
fix_print_path.patch (application/octet-stream, 834B) download
diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c
index 3ada379..eb0018b 100644
--- a/src/backend/optimizer/path/allpaths.c
+++ b/src/backend/optimizer/path/allpaths.c
@@ -3689,6 +3689,9 @@ print_path(PlannerInfo *root, Path *path, int indent)
case T_ForeignPath:
ptype = "ForeignScan";
break;
+ case T_CustomPath:
+ ptype = "CustomScan";
+ break;
case T_AppendPath:
ptype = "Append";
break;
@@ -3710,6 +3713,10 @@ print_path(PlannerInfo *root, Path *path, int indent)
ptype = "Gather";
subpath = ((GatherPath *) path)->subpath;
break;
+ case T_GatherMergePath:
+ ptype = "GatherMerge";
+ subpath = ((GatherMergePath *) path)->subpath;
+ break;
case T_ProjectionPath:
ptype = "Projection";
subpath = ((ProjectionPath *) path)->subpath;
* Re: print_path is missing GatherMerge and CustomScan support
@ 2018-07-18 06:22 Michael Paquier <michael@paquier.xyz>
parent: Masahiko Sawada <sawada.mshk@gmail.com>
0 siblings, 2 replies; 14+ messages in thread
From: Michael Paquier @ 2018-07-18 06:22 UTC (permalink / raw)
To: Masahiko Sawada <sawada.mshk@gmail.com>; +Cc: pgsql-hackers; Robert Haas <robertmhaas@gmail.com>; Ashutosh Bapat <ashutosh.bapat@gmail.com>
On Wed, Jul 18, 2018 at 02:35:23PM +0900, Masahiko Sawada wrote:
> Hi,
>
> While debugging planner I realized that print_path() function is not
> aware of both GatherMerge path and CustomScan path. Attached small
> patch fixes it.
Good catch. Those should be backpatched. While I am looking at this
stuff, I have noticed that pathnode.c/reparameterize_path_by_child uses
T_MergeAppend and not T_MergeAppendPath.
inline patch 1: src/backend/optimizer/util/pathnode.c (+1/-1 lines) download inline-1.patch
--- a/src/backend/optimizer/util/pathnode.c
+++ b/src/backend/optimizer/util/pathnode.c
@@ -3817,7 +3817,7 @@ do { \
}
break;
- case T_MergeAppend:
+ case T_MergeAppendPath:
{
MergeAppendPath *mapath
* Re: print_path is missing GatherMerge and CustomScan support
@ 2018-07-18 06:45 Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>
parent: Michael Paquier <michael@paquier.xyz>
1 sibling, 2 replies; 14+ messages in thread
From: Ashutosh Bapat @ 2018-07-18 06:45 UTC (permalink / raw)
To: Michael Paquier <michael@paquier.xyz>; +Cc: Masahiko Sawada <sawada.mshk@gmail.com>; pgsql-hackers; Robert Haas <robertmhaas@gmail.com>; Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>
On Wed, Jul 18, 2018 at 11:52 AM, Michael Paquier <michael@paquier.xyz> wrote:
> On Wed, Jul 18, 2018 at 02:35:23PM +0900, Masahiko Sawada wrote:
>> Hi,
>>
>> While debugging planner I realized that print_path() function is not
>> aware of both GatherMerge path and CustomScan path. Attached small
>> patch fixes it.
>
> Good catch. Those should be backpatched. While I am looking at this
> stuff, I have noticed that pathnode.c/reparameterize_path_by_child uses
> T_MergeAppend and not T_MergeAppendPath.
>
> --- a/src/backend/optimizer/util/pathnode.c
> +++ b/src/backend/optimizer/util/pathnode.c
> @@ -3817,7 +3817,7 @@ do { \
> }
> break;
>
> - case T_MergeAppend:
> + case T_MergeAppendPath:
> {
> MergeAppendPath *mapath
>
> This is new as of f49842d1 in v11.
Yes that's right. Thanks for taking care of it.
> Robert, Ashutosh, am I missing
> something?
You used my personal email id by mistake, I think. I have removed it
and added by EDB email address.
--
Best Wishes,
Ashutosh Bapat
EnterpriseDB Corporation
The Postgres Database Company
^ permalink raw reply [nested|flat] 14+ messages in thread
* Re: print_path is missing GatherMerge and CustomScan support
@ 2018-07-18 06:55 Michael Paquier <michael@paquier.xyz>
parent: Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>
1 sibling, 0 replies; 14+ messages in thread
From: Michael Paquier @ 2018-07-18 06:55 UTC (permalink / raw)
To: Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>; +Cc: Masahiko Sawada <sawada.mshk@gmail.com>; pgsql-hackers; Robert Haas <robertmhaas@gmail.com>
On Wed, Jul 18, 2018 at 12:15:25PM +0530, Ashutosh Bapat wrote:
> On Wed, Jul 18, 2018 at 11:52 AM, Michael Paquier <michael@paquier.xyz> wrote:
>> On Wed, Jul 18, 2018 at 02:35:23PM +0900, Masahiko Sawada wrote:
>>> Hi,
>>>
>>> While debugging planner I realized that print_path() function is not
>>> aware of both GatherMerge path and CustomScan path. Attached small
>>> patch fixes it.
>>
>> Good catch. Those should be backpatched. While I am looking at this
>> stuff, I have noticed that pathnode.c/reparameterize_path_by_child uses
>> T_MergeAppend and not T_MergeAppendPath.
>>
>> This is new as of f49842d1 in v11.
>
> Yes that's right. Thanks for taking care of it.
Thanks for the confirmation. Robert, do you want to take care of this
issue or should I?
>> Robert, Ashutosh, am I missing
>> something?
>
> You used my personal email id by mistake, I think. I have removed it
> and added by EDB email address.
My sincere apologies. I have not been careful.
--
Michael
Attachments:
signature.asc (application/pgp-signature, 832B) download
^ permalink raw reply [nested|flat] 14+ messages in thread
* Re: print_path is missing GatherMerge and CustomScan support
@ 2018-07-19 00:07 Michael Paquier <michael@paquier.xyz>
parent: Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>
1 sibling, 1 reply; 14+ messages in thread
From: Michael Paquier @ 2018-07-19 00:07 UTC (permalink / raw)
To: Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>; +Cc: Masahiko Sawada <sawada.mshk@gmail.com>; pgsql-hackers; Robert Haas <robertmhaas@gmail.com>
On Wed, Jul 18, 2018 at 12:15:25PM +0530, Ashutosh Bapat wrote:
> Yes that's right. Thanks for taking care of it.
Okay, I have pushed a fix for this one as that's wrong and
back-patched to v11. The coverage of reparameterize_path_by_child is
actually quite poor if you look at the reports:
https://coverage.postgresql.org/src/backend/optimizer/util/pathnode.c.gcov.html
Could it be possible to stress that more? This way mistakes like this
one could have been avoided from the start.
--
Michael
Attachments:
signature.asc (application/pgp-signature, 832B) download
^ permalink raw reply [nested|flat] 14+ messages in thread
* Re: print_path is missing GatherMerge and CustomScan support
@ 2018-07-19 00:58 Michael Paquier <michael@paquier.xyz>
parent: Michael Paquier <michael@paquier.xyz>
1 sibling, 1 reply; 14+ messages in thread
From: Michael Paquier @ 2018-07-19 00:58 UTC (permalink / raw)
To: Masahiko Sawada <sawada.mshk@gmail.com>; +Cc: pgsql-hackers; Robert Haas <robertmhaas@gmail.com>; Ashutosh Bapat <ashutosh.bapat@gmail.com>
On Wed, Jul 18, 2018 at 03:22:02PM +0900, Michael Paquier wrote:
> Good catch. Those should be backpatched. While I am looking at this
> stuff, I have noticed that pathnode.c/reparameterize_path_by_child uses
> T_MergeAppend and not T_MergeAppendPath.
Okay, I have checked the full list of path nodes and the two ones you
mentioned are the only missing. CustomPath has been added in 9.5, so
this has been patched down to this version. GatherMergePath is new as
of 10.
The order of the items in print_path and nodes.h was a bit messed up as
well which made unnecessarily harder to check the list, so I fixed the
order at the same time to ease future lookups and back-patching effort.
--
Michael
Attachments:
signature.asc (application/pgp-signature, 832B) download
^ permalink raw reply [nested|flat] 14+ messages in thread
* Re: print_path is missing GatherMerge and CustomScan support
@ 2018-07-19 05:11 Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>
parent: Michael Paquier <michael@paquier.xyz>
0 siblings, 2 replies; 14+ messages in thread
From: Ashutosh Bapat @ 2018-07-19 05:11 UTC (permalink / raw)
To: Michael Paquier <michael@paquier.xyz>; +Cc: Masahiko Sawada <sawada.mshk@gmail.com>; pgsql-hackers; Robert Haas <robertmhaas@gmail.com>
On Thu, Jul 19, 2018 at 5:37 AM, Michael Paquier <michael@paquier.xyz> wrote:
> On Wed, Jul 18, 2018 at 12:15:25PM +0530, Ashutosh Bapat wrote:
>> Yes that's right. Thanks for taking care of it.
>
> Okay, I have pushed a fix for this one as that's wrong and
> back-patched to v11. The coverage of reparameterize_path_by_child is
> actually quite poor if you look at the reports:
> https://coverage.postgresql.org/src/backend/optimizer/util/pathnode.c.gcov.html
>
> Could it be possible to stress that more? This way mistakes like this
> one could have been avoided from the start.
I had extensive testcases in my original patch-set to exercise that
code but 1. that testset was too extensive; even today
partition_join.sql is a separate testcase and it's quite large. 2.
that function returns NULL rather than throwing an error, if it can
not produce a parameterized path. So, unless we check whether each of
those paths get created no test is useful and that can only be done
through an EXPLAIN OUTPUT which means that the testcase becomes
fragile. I fine if we want to add more tests just to cover the code if
those are not as fragile and do not blow up partition_join too much.
--
Best Wishes,
Ashutosh Bapat
EnterpriseDB Corporation
The Postgres Database Company
^ permalink raw reply [nested|flat] 14+ messages in thread
* Re: print_path is missing GatherMerge and CustomScan support
@ 2018-07-19 06:26 Michael Paquier <michael@paquier.xyz>
parent: Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>
1 sibling, 1 reply; 14+ messages in thread
From: Michael Paquier @ 2018-07-19 06:26 UTC (permalink / raw)
To: Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>; +Cc: Masahiko Sawada <sawada.mshk@gmail.com>; pgsql-hackers; Robert Haas <robertmhaas@gmail.com>
On Thu, Jul 19, 2018 at 10:41:10AM +0530, Ashutosh Bapat wrote:
> I had extensive testcases in my original patch-set to exercise that
> code but 1. that testset was too extensive; even today
> partition_join.sql is a separate testcase and it's quite large. 2.
> that function returns NULL rather than throwing an error, if it can
> not produce a parameterized path. So, unless we check whether each of
> those paths get created no test is useful and that can only be done
> through an EXPLAIN OUTPUT which means that the testcase becomes
> fragile. I fine if we want to add more tests just to cover the code if
> those are not as fragile and do not blow up partition_join too much.
Did those really check the reparameterization of a MergeAppendPath for a
child of the parent? I'd be surprised if this one was stressed as there
was no match in the list.
--
Michael
Attachments:
signature.asc (application/pgp-signature, 832B) download
^ permalink raw reply [nested|flat] 14+ messages in thread
* Re: print_path is missing GatherMerge and CustomScan support
@ 2018-07-19 06:36 Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>
parent: Michael Paquier <michael@paquier.xyz>
0 siblings, 0 replies; 14+ messages in thread
From: Ashutosh Bapat @ 2018-07-19 06:36 UTC (permalink / raw)
To: Michael Paquier <michael@paquier.xyz>; +Cc: Masahiko Sawada <sawada.mshk@gmail.com>; pgsql-hackers; Robert Haas <robertmhaas@gmail.com>
On Thu, Jul 19, 2018 at 11:56 AM, Michael Paquier <michael@paquier.xyz> wrote:
> On Thu, Jul 19, 2018 at 10:41:10AM +0530, Ashutosh Bapat wrote:
>> I had extensive testcases in my original patch-set to exercise that
>> code but 1. that testset was too extensive; even today
>> partition_join.sql is a separate testcase and it's quite large. 2.
>> that function returns NULL rather than throwing an error, if it can
>> not produce a parameterized path. So, unless we check whether each of
>> those paths get created no test is useful and that can only be done
>> through an EXPLAIN OUTPUT which means that the testcase becomes
>> fragile. I fine if we want to add more tests just to cover the code if
>> those are not as fragile and do not blow up partition_join too much.
>
> Did those really check the reparameterization of a MergeAppendPath for a
> child of the parent? I'd be surprised if this one was stressed as there
> was no match in the list.
I don't remember but given this evident, it was not. But there are
some testcases in partition_join which test this code using LATERAL
joins. But those do not cover the entire function.
--
Best Wishes,
Ashutosh Bapat
EnterpriseDB Corporation
The Postgres Database Company
^ permalink raw reply [nested|flat] 14+ messages in thread
* Re: print_path is missing GatherMerge and CustomScan support
@ 2018-07-19 09:38 Masahiko Sawada <sawada.mshk@gmail.com>
parent: Michael Paquier <michael@paquier.xyz>
0 siblings, 0 replies; 14+ messages in thread
From: Masahiko Sawada @ 2018-07-19 09:38 UTC (permalink / raw)
To: Michael Paquier <michael@paquier.xyz>; +Cc: pgsql-hackers; Robert Haas <robertmhaas@gmail.com>; Ashutosh Bapat <ashutosh.bapat@gmail.com>
On Thu, Jul 19, 2018 at 9:58 AM, Michael Paquier <michael@paquier.xyz> wrote:
> On Wed, Jul 18, 2018 at 03:22:02PM +0900, Michael Paquier wrote:
>> Good catch. Those should be backpatched. While I am looking at this
>> stuff, I have noticed that pathnode.c/reparameterize_path_by_child uses
>> T_MergeAppend and not T_MergeAppendPath.
>
> Okay, I have checked the full list of path nodes and the two ones you
> mentioned are the only missing. CustomPath has been added in 9.5, so
> this has been patched down to this version. GatherMergePath is new as
> of 10.
>
> The order of the items in print_path and nodes.h was a bit messed up as
> well which made unnecessarily harder to check the list, so I fixed the
> order at the same time to ease future lookups and back-patching effort.
Thank you for committing the patch!
Regards,
--
Masahiko Sawada
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center
^ permalink raw reply [nested|flat] 14+ messages in thread
* Re: print_path is missing GatherMerge and CustomScan support
@ 2018-07-26 05:14 Etsuro Fujita <fujita.etsuro@lab.ntt.co.jp>
parent: Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>
1 sibling, 1 reply; 14+ messages in thread
From: Etsuro Fujita @ 2018-07-26 05:14 UTC (permalink / raw)
To: Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>; +Cc: Michael Paquier <michael@paquier.xyz>; Masahiko Sawada <sawada.mshk@gmail.com>; pgsql-hackers; Robert Haas <robertmhaas@gmail.com>
(2018/07/19 14:11), Ashutosh Bapat wrote:
> On Thu, Jul 19, 2018 at 5:37 AM, Michael Paquier<michael@paquier.xyz> wrote:
>> On Wed, Jul 18, 2018 at 12:15:25PM +0530, Ashutosh Bapat wrote:
>>> Yes that's right. Thanks for taking care of it.
>>
>> Okay, I have pushed a fix for this one as that's wrong and
>> back-patched to v11. The coverage of reparameterize_path_by_child is
>> actually quite poor if you look at the reports:
>> https://coverage.postgresql.org/src/backend/optimizer/util/pathnode.c.gcov.html
>>
>> Could it be possible to stress that more? This way mistakes like this
>> one could have been avoided from the start.
>
> I had extensive testcases in my original patch-set to exercise that
> code but 1. that testset was too extensive; even today
> partition_join.sql is a separate testcase and it's quite large. 2.
> that function returns NULL rather than throwing an error, if it can
> not produce a parameterized path. So, unless we check whether each of
> those paths get created no test is useful and that can only be done
> through an EXPLAIN OUTPUT which means that the testcase becomes
> fragile. I fine if we want to add more tests just to cover the code if
> those are not as fragile and do not blow up partition_join too much.
It would not be possible to cover these cases:
case T_GatherPath:
{
GatherPath *gpath;
FLAT_COPY_PATH(gpath, path, GatherPath);
REPARAMETERIZE_CHILD_PATH(gpath->subpath);
new_path = (Path *) gpath;
}
break;
case T_GatherMergePath:
{
GatherMergePath *gmpath;
FLAT_COPY_PATH(gmpath, path, GatherMergePath);
REPARAMETERIZE_CHILD_PATH(gmpath->subpath);
new_path = (Path *) gmpath;
}
break;
because we currently don't consider gathering partial child-scan or
child-join paths. I think we might consider that in future, though.
Best regards,
Etsuro Fujita
^ permalink raw reply [nested|flat] 14+ messages in thread
* Re: print_path is missing GatherMerge and CustomScan support
@ 2018-07-26 19:50 Robert Haas <robertmhaas@gmail.com>
parent: Etsuro Fujita <fujita.etsuro@lab.ntt.co.jp>
0 siblings, 1 reply; 14+ messages in thread
From: Robert Haas @ 2018-07-26 19:50 UTC (permalink / raw)
To: Etsuro Fujita <fujita.etsuro@lab.ntt.co.jp>; +Cc: Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>; Michael Paquier <michael@paquier.xyz>; Masahiko Sawada <sawada.mshk@gmail.com>; pgsql-hackers
On Thu, Jul 26, 2018 at 1:14 AM, Etsuro Fujita
<fujita.etsuro@lab.ntt.co.jp> wrote:
> because we currently don't consider gathering partial child-scan or
> child-join paths. I think we might consider that in future, though.
You generally want to put the Gather node as high up in the plan tree
as possible. I think the only case in which this is beneficial is if
you can't put the Gather or Gather Merge node above the Append because
only some of the children are parallel-safe. In that case, a separate
Gather per child can be better than no parallelism at all. It's a
rare case, but it can happen. Actually, I thought we had code for this
already: see the end of apply_scanjoin_target_to_paths().
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
^ permalink raw reply [nested|flat] 14+ messages in thread
* Re: print_path is missing GatherMerge and CustomScan support
@ 2018-07-27 06:40 Etsuro Fujita <fujita.etsuro@lab.ntt.co.jp>
parent: Robert Haas <robertmhaas@gmail.com>
0 siblings, 1 reply; 14+ messages in thread
From: Etsuro Fujita @ 2018-07-27 06:40 UTC (permalink / raw)
To: Robert Haas <robertmhaas@gmail.com>; +Cc: Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>; Michael Paquier <michael@paquier.xyz>; Masahiko Sawada <sawada.mshk@gmail.com>; pgsql-hackers
(2018/07/27 4:50), Robert Haas wrote:
> On Thu, Jul 26, 2018 at 1:14 AM, Etsuro Fujita
> <fujita.etsuro@lab.ntt.co.jp> wrote:
>> because we currently don't consider gathering partial child-scan or
>> child-join paths. I think we might consider that in future, though.
>
> You generally want to put the Gather node as high up in the plan tree
> as possible. I think the only case in which this is beneficial is if
> you can't put the Gather or Gather Merge node above the Append because
> only some of the children are parallel-safe. In that case, a separate
> Gather per child can be better than no parallelism at all. It's a
> rare case, but it can happen. Actually, I thought we had code for this
> already: see the end of apply_scanjoin_target_to_paths().
Agreed. Thanks for the explanation!
(I think that at least currently, there is no need for the Gather and
GatherMerge cases in reparameterize_path_by_child, but I don't object to
keeping those as-is there.)
Best regards,
Etsuro Fujita
^ permalink raw reply [nested|flat] 14+ messages in thread
* Re: print_path is missing GatherMerge and CustomScan support
@ 2018-07-27 07:02 Michael Paquier <michael@paquier.xyz>
parent: Etsuro Fujita <fujita.etsuro@lab.ntt.co.jp>
0 siblings, 0 replies; 14+ messages in thread
From: Michael Paquier @ 2018-07-27 07:02 UTC (permalink / raw)
To: Etsuro Fujita <fujita.etsuro@lab.ntt.co.jp>; +Cc: Robert Haas <robertmhaas@gmail.com>; Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>; Masahiko Sawada <sawada.mshk@gmail.com>; pgsql-hackers
On Fri, Jul 27, 2018 at 03:40:48PM +0900, Etsuro Fujita wrote:
> (I think that at least currently, there is no need for the Gather and
> GatherMerge cases in reparameterize_path_by_child, but I don't object to
> keeping those as-is there.)
Let's keep them. As far as my understanding goes, which is way lower
than any of you by the way, those don't hurt and would automatically
help.
--
Michael
Attachments:
signature.asc (application/pgp-signature, 832B) download
^ permalink raw reply [nested|flat] 14+ messages in thread
end of thread, other threads:[~2018-07-27 07:02 UTC | newest]
Thread overview: 14+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2018-07-18 05:35 print_path is missing GatherMerge and CustomScan support Masahiko Sawada <sawada.mshk@gmail.com>
2018-07-18 06:22 ` Michael Paquier <michael@paquier.xyz>
2018-07-18 06:45 ` Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>
2018-07-18 06:55 ` Michael Paquier <michael@paquier.xyz>
2018-07-19 00:07 ` Michael Paquier <michael@paquier.xyz>
2018-07-19 05:11 ` Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>
2018-07-19 06:26 ` Michael Paquier <michael@paquier.xyz>
2018-07-19 06:36 ` Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>
2018-07-26 05:14 ` Etsuro Fujita <fujita.etsuro@lab.ntt.co.jp>
2018-07-26 19:50 ` Robert Haas <robertmhaas@gmail.com>
2018-07-27 06:40 ` Etsuro Fujita <fujita.etsuro@lab.ntt.co.jp>
2018-07-27 07:02 ` Michael Paquier <michael@paquier.xyz>
2018-07-19 00:58 ` Michael Paquier <michael@paquier.xyz>
2018-07-19 09:38 ` Masahiko Sawada <sawada.mshk@gmail.com>
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